This invention relates to a support assembly to be used in association with a sealing arrangement to support a member which is movable with respect to a base element. In particular, this invention relates to a support assembly used to support the pull rod of a pump assembly adjacent the seal for the pull rod.
This invention is an improvement of the support assembly described in our earlier Australian patent 674209, the content of which is incorporated herein by reference.
The problem of providing an adequate seal for members which are movable with respect to a base, such as rotating shafts or reciprocating pull rods, is well known. This problem is made worse when the rotating or reciprocating member is caused to undergo relative lateral or angular displacement with respect to the housing in the region of the seal.
Generally, most parts of the support arrangement are machined and it is often difficult to provide an adequate seal. Further, if the rotating or reciprocating member has been misaligned or is bent, a portion of the shaft can be caused to xe2x80x9corbitxe2x80x9d around its central axis during the rotation cycle. This misalignment can occur where the drive means for the member is out of alignment with the central axis of the member or where due to a fault in the drive means the pump rod is caused to be flexed out of alignment during each stroke of the drive means.
In the past a variety of support arrangements have been proposed for accommodating for lateral or angular displacement of a movable member with respect to a housing, however these arrangements have not proved to be satisfactory where the movable member may be subjected to heavy tensional loads as in the case where a pump pull rod or high differential fluid pressure acts on the support assembly or seal.
An example of a support arrangement is disclosed in Australian patent specification 625322 which discloses a guide for a movable shaft which accommodates for lateral and angular displacement of a pump pull rod with respect to a housing. It has been found, however, that while this arrangement has in many cases proved to be satisfactory where that assembly has been subjected to high load as a result of fluid pressure within the wellhead, high point loadings have been established between the bearing member and the bearing rings of the assembly which has limited the freedom of movement between the bearing member and the housing.
Our earlier Australian patent 674209 describes a self-aligning shaft support incorporating a pair of spherical bearing members that allow both lateral and angular movement of the pull rod. However, it allows the fluid being pumped into the bearing chamber. The abrasive nature of that fluid may cause speedy failure of the bearings and/or the associated seals.
It is an object of this invention to provide an improved self-aligning shaft support which allows both relative lateral and angular displacement of the shaft under high pressure conditions.
The invention accordingly provides a guide for supporting a first member in a housing where said first member is capable of rotational and reciprocal movement relative to the housing; said guide including a bearing housing having a first angled face, said bearing housing supporting a guide element, said guide element including a central member having an axial passage therethrough which is adapted to sealingly receive the first member to permit said rotational and reciprocal movement, said guide member further including a substantially annular flange element which is received within the bearing housing adjacent the first angled face thereof, said guide member being supported from the first angled face by an annular bearing element, located between one axial face of the flange element and the first angled face of the bearing housing, wherein said bearing housing includes a base having said first angled face and a cap that cooperates with the guide member, said cap including a lower angled face cooperable with a second angled face provided on said base, and wherein the first angled face of the bearing housing and an angled face of the bearing element with which the first angled face is cooperable are of a substantially spherical configuration to enable angular displacement of the guide member relative to said base, and said second and lower angled faces are of substantially spherical configuration to enable angular displacement of the cap relative to the base.
More preferably, said first angled face and said second and lower angled faces have substantially the same radius of curvature.
Preferably, said cap includes a detachable lower portion which extends inwardly towards said axial passage, said lower portion including said lower angled face.
Preferably, said base includes an outwardly extending flange portion, said flange portion including said second angled face.
Preferably the centre of curvature of each spherical face is located on the central axis of the central member.
Preferably, the bearing housing includes a second axial face, substantially opposed to the first axial face. More preferably, said second axial face includes a bearing, wherein said bearing facilitates relative movement between another axial face of the flange element and the second axial face of the bearing housing. Preferably, the second axial face of the bearing housing is substantially perpendicular to the central axis of the central member.